This invention relates to high pressure, fluid-driven tension actuators and the method for constructing such actuators. Tension actuators convert fluid pressure energy input, for example such as compressed air energy, into mechanical output. More specifically, they convert fluid pressure energy into linear contraction displacement.
The general purpose of the present invention is to provide novel tension actuators capable of inflation to a high pressure and methods for making such actuators. Further, the invention provides such actuators capable of high-frequency operation, i.e., numerous cycles of inflation and deflation per second, and capable of being actuated over a wide range of operating pressures, in a safe manner.
As I have used the term "high pressure" in this field of tension actuators, it means having a pressure of at least two atmospheres or more, i.e., more than 29 pounds per square inch.
The concept of a tension actuator which contracts along its longitudinal axis when inflated is known. Such an actuator, which responds at relatively low fluid pressure, is disclosed in U.S. Pat. No. 3,645,173--Yarlott. That fluid actuator is described as operating at 0.25 pounds per square inch. Another device which axially contracts upon inflation is disclosed in British Pat. No. 674,031--Morin. U.S. Pat. No. 3,638,536--Kleinwachter et al discloses diaphragm devices for transforming a fluid pressure into torsional movement or into axial movement upon inflation. U.S. Pat. No. 2,789,580--Woods discloses a mechanical transducer with an expansible cavity formed by a flexible seal having a cylindrical braided or woven metal sheath encompassing it.
U.S. Pat. No. 2,865,419--Cunningham has been reviewed by the present inventor and is considered even more remote from the present invention than the above disclosures. It is set forth as being known to the inventor in order for this list of known disclosures to be complete and in the event the reader might consider it to be of interest.